Adaptive Signal Filtering for Smooth Parameter Transitions
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Solution Overview
Problem
Conventional filtering techniques for time-varying audio and speech signals, such as those used in codecs, often result in instabilities and discontinuities due to the need for frequent updates of adaptive filter parameters, leading to increased complexity and computational requirements.
Innovation Solution
A system and method that employs two filter units to gradually scale filter parameters within an initial subinterval of an update interval, transitioning from a higher-filtering status to a lower-filtering status and vice versa, reducing the need for cross-fading and minimizing computational complexity by performing two filtering operations instead of two separate operations followed by cross-fading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If adaptive filter parameters are updated frequently to track time-varying audio/speech signals, then filtering adaptability is improved, but signal stability deteriorates due to instabilities and discontinuities
Solution Approach 1:
The patent applies preliminary action by performing a first filtering operation using parameters from the preceding update interval before applying the current update interval parameters. This preparatory filtering step ensures smooth transitions and prevents discontinuities when parameters change, thereby maintaining signal stability while still adapting to time-varying characteristics.
Solution Approach 2:
The patent implements dynamics by making the filter parameters time-varying within each update interval. Instead of using constant parameters throughout an update interval, the filter dynamically adjusts parameters based on the signal characteristics, allowing the system to adapt to changing conditions while maintaining stability through controlled transitions.
2Stability of the object's composition
If cross-fade approach is used to remove discontinuities in adaptively filtered signals, then signal stability is improved, but device complexity increases
Solution Approach 1:
The patent merges the first filtering operation and the second filtering operation into a unified filtering process. Instead of performing separate filtering operations followed by a cross-fade mixing step, the patent combines these operations such that the transition between parameter sets is achieved through the filtering process itself, reducing computational complexity while maintaining signal stability.
3Manufacturing precision
If two separate filtering operations are performed to handle parameter updates, then filtering precision is improved, but computational overhead increases
Solution Approach 1:
The patent performs the first filtering operation as a preliminary step before the second filtering operation. This preliminary filtering using preceding update interval parameters prepares the signal in advance, allowing the second filtering operation to focus on applying current parameters efficiently. This staged approach maintains filtering precision while optimizing computational resource usage.
Data Source
AI summary
In methods and systems for filtering an information input signal, a system may have: a first filter unit filtering an input signal at an initial subinterval in a current update interval according to parameters associated to the preceding update interval, the parameters being scaled by a first scaling factor changing towards 0; and a second filter unit filtering a second filter input signal, based on the output of the first filter unit, at the initial subinterval, according to parameters associated to the current update interval, the parameters being scaled by a second scaling factor changing from 0, or a value close to 0, toward a value more distant from 0.